Top closure for high temperature electrostatic precipitator



L. MAFRICA Dec. 27, 1966 TOP CLOSURE FOR HIGH TEMPERATURE ELECTROSTATIC PRECIPITATOR 2 Sheets-Sheet 1 Filed Aug. 27 1963 INVENTOR L 50 MAFR/GA ORNEYS L. MAFRICA Dec. 27, 1966 TOP CLOSURE FOR HIGH TEMPERATURE ELECTROSTATIC PRECIPITATOR 2 Sheets-Sheet 2 Filed Aug. 27 1963 5 mm m mm m n MM 0 ig Q m n United States Patent 3,293,829 TOP CLOSURE FOR HIGH TEMPERATURE ELECTROSTATIC PRECIPITATOR Leo Mafrica, Pittsburgh, Pa., assignor to the United States of America as represented by the Secretary of the Interior Filed Aug. 27, 1963, Ser. No. 305,014 Claims. (Cl. 55-104) The invention herein described and claimed may be used by or for the Government of the United States of America for governmental purposes without the payment of royalties thereon or therefor.

This invention relates generally to electrostatic precipitator equipment which functions to collect particles in gases supplied thereto at relatively high temperatures. More particularly, it concerns improvements to this precipitators top closure arrangement wherein the structure comprising the high voltage electrode assembly of the precipitator is normally supported. Adjustable means comprising the improved arrangement constitutes a flexible mount for supporting the high voltage or discharge electrode at a proper location in the precipitator, and includes as a part thereof, the electrical insulation needed between the electrodes of opposite polarity across which the high voltage electrostatic field is maintained. In addition there is cooperatively associated in this improvement an auxiliary arrangement by means of which the centering or alignment of the discharge electrode in respect to the collector electrode can be conveniently accomplished with a high degree of exactitude.

Eflectual precipitator treatment of gases at high temperatures having a high content of fine particulate material such as carry-over lines of carbon derived from a fluidized bed of high temperature coke in a carbonization and cracking process for thermally cracking tar vapors, presents a diflicult problem. If removal of the fine carbon and other dust materials in the gas stream flowing from the cracker is not sufliciently attained, these materials condense with the tar products, making the tar analyses diflicult and inaccurate. Filters, cyclones, and other forms of precipitators presently available, are generally not suited to cope with the high particle content of the cracked carbon, or the high temperature, or both, encountered in the cracking process. However, the present invention makes available a construction which does allow a more propitious handling of those difficulties that are inherent in cleaning fluidized coal gases. The structure of the invention is easily assembled and disassembled for cleaning as frequently as required, and provides a closure seal permitting a pressure build-up in the precipitator which is conducive to more eflicient precipitation. Moreover, nearly all the fines entrained in the gas are precipitated wherein most of the remaining fine carbon is agglomerated into particles large enough to be removed by subsequent cyclone action. Further, the closure seal of the present invention includes an insulator part which is sufliciently adjustable to greatly simplify the centering of the high voltage electrode secured thereto, with a resultant retardation of electrostatic breakdowns in the precipitator. Also functioning to expedite the centering of the high voltage electrode is an indicator means which is openatively responsive to a coaction between position sensing elements comprising the auxiliary arrangement and the electrode.

It is therefore an object of the present invention to provide for use in an electrostatic precipitator a removable gas-tight closure having high electrical resistivity at high temperatures.

Another object of the invention is to provide in an electrostatic precipitator, an adjustable insulator closure threads on its outer cylindrical surface.

3 ,293,829 Patented Dec. 27, 1966 ICC seal adapted to support the high voltage electrode of the precipitator in an accurately centered position relative to its surrounding enclosure.

A still further object of the invention is to provide an arrangement facilitating the positioning of a top closure for an electrostatic precipitator wherein an insulator element is adjustably positionable upon a flexible pressure seal to maintain a high voltage electrode closely aligned along the central axis of the precipitator.

These and other objects and advantages of the invention will be more readily understood from the following detailed description of the preferred embodiments of the invention considered together with the figures of the accompanying drawing wherein:

FIG. 1 is a fragmentary elevational view, partly in section, of an electrostatic precipitator adapted to utilize a particular embodiment of the present invention;

FIG. 2 is .a generally schematic illustration of the electrically operated position detector and indicator arrangement comprising the present invention; and

FIGS. 3 and 4 are fragmentary, partly cross-sectional views of the upper portion of electrostatic precipitators adapted to utilize dilferent modifications of the present invention.

In FIG. 1 member 10 represents an elongated cylindri cal metal body comprising the central tubular portion of a conventional Cottrell-type electrostatic precipitator. Exemplary of the form which such precipitators may take are the structural arrangements disclosed in Patent No. 1,837,489, issued to H. R. Rowland on Dec. 22, 1931, and Patent No. 3,054,243, issued to W. S. Bowie, on Sept. 18, 1962. At the uppermost part of the tubular member 10, an end portion 111 is supplied with screw Encircling the opening in the end portion, is a relatively thick, disklike header flange 13. Opening on an upper face 14 of the flange is an enlarged central hole 15 from which a conical depression descends int-o slightly more than half the thickness of the flange, to define at the bottom of its converging wall 16, an internal opening 17. Opening on to an underside surface 18 of the flange, is a centrally situated cylindrical cavity 19, whose inner ends join the internal opening 16 at an interior circular rim or shoulder 20. Cavity 19 is internally threaded whereby the threaded end portion 11 of the member 10 by engagement therein is adapted to fit against the shoulder 20.

Formed into the outer edge of hole .15 and the adjacent surface of converging wall 16, is an angularly disposed, channel-like, rectangular groove 22 whose straight side 23 intersects the wall 16 at approximately a right angle. Snugly filling the groove 22, is a ring of high-temperature packing material 24, which extends beyond the wall 16, and slightly above the flange face 14. Packing 24 which has a generally rectangular cross-section, can be made of asbestos braiding or other material of equivalent packing and temperature characteristics that will withstand a temperature of at least 500 C.

Set into the passage defined by the several openings in the member 10 and flange 13, and initially resting upon the inclined surfaces of the packing ring 24, is a plug-like member 25 constituting an insulator for the high-voltage electrode 26 of the precipitator, which as shown in the figure comprises a rigid piece of metal tubing or rod of suitable length and metal composition. Insulator member 25 is made of a ceramic or like material, and shaped like a frustrum of a right cone whereby its slanted curved surface conforms to the incline of the seat fashioned by the angularly disposed surfaces of the wall 16 and packing 24. Extending axially through insulator member 25 is a hole 27 whose opposed ends merge into the water countersunk openings 28 and 29 in the insulators larger upper flat face 30, and smaller bottom fiat face 31, respectively. Filling each of the respective openings 28 and 29, are high-temperature packings 33 and 34 composed of material similar to that used for packing ring 24. Extending out from the top of the electrode 26, is a reduced diameter spindle 36, which is received through hole 27, and the packings 33 and 34. Screw threads provided on the extended end of spindle 36 are engaged by a nut 37, which is operable when tightened down on a washer 38 covering over a slightly raised upper surface of packing 33, to securely fasten the electrode 26 to the insulator member 25, and seal the hole 27.

At three or more points a short distance from the outer periphery of the flange 13, and uniformly spaced from and about the central hole thereof, are fastened specially formed clamping devices. As will be hereinafter more fully explained, these devices are operably coordimated to apply pressure on the insulator member whereby the packing ring 24 is deformed to effect a sealed closure for the top header of the precipitator, and at the same time permitting an almost exact centering of the electrode 26 therein. The separate clamping devices each correspond to the form of devices 443 and 42 shown in the figure of the drawing, and include a Z-shaped member 44 comprising an upper arm 45 in which a threaded hole is provided to receive an adjusting screw 46. Conventional nut and bolt means 43 are used to adjustably retain these devices to the flange 13. As is evident in the figure, fastening means 48 are operable to secure a lower arm 49 of the Z-member to the upper face 14 of the flange whereby it fixes the Z-member in a position to locate an adjusting screw 46 over a peripheral portion of the upper face on the insulator 25. A fiat metal ring 50, resting on the upper insulator face 30 so as to cover a substantially wide rim section of the peripheral portion of this face, underlies the plurality of adjusting screws 46. Ring 50 is thereby in position to receive the point pressures of the adjusting screws and effectively prevent these screws from damaging the insulator member 25 during assembly and adjustment operations.

Assembly of the top closure to the precipitator structure initially requires that a leakproof connection between the electrode 26 and its insulator 25, be obtained. It is evident that tightening nut 37 on the threads of spindle 36, will accomplish this connection by the compression applied to the packings 33 and 34, from the washer 38, and the shoulder formed by the undercut on electrode 26 at the base of the spindle. Thereafter, the electrode 26 is lowered into the precipitator to bring the conical surface of its insulator 25 to rest evenly upon the packing ring 24. Members 44 of the clamping devices are attached to the flange 13, or if then in place, merely pivoted about their fastening means 48, to properly locate the adjusting screws 46 over the protection ring 50. Because the packing 24 extends beyond the top of the channel 22, the insulator 25 can be made to rock or swivel by appropriately loosening or tightening the adjusting screws. Such play in this flexible arrangement facilitates achieving a sharply defined or near perfect centering of the electrode 26 within the precipitator tube It Careful centering in this manner is of paramount importance for maximum precipitator performance as it prevents possible frequent electrostatic breakdowns under such adverse conditions as high temperature and heavy particle precipitation. Final adjustments can then be made equally to each of the screws 46 to obtain the uniform tightness necessary for a leakproof seal around the insulator. A glaze on the outer surface of the insulator 25 which makes possible a better leakproof fit against the packing 24, is also effective to retard the adhesion of fines on the insulator surface exposed to the gases within the precipitator. Upon completion of the adjustment and sealing of the top closure, a lead 51 from the high voltage supply is connected by nuts 52 to the extended end of the electrode spindle 36.

To ascertain that the electrode 26 is set to be nearly perfectly aligned on the axis of tubular member 10 when the aforementioned final adjustments to each of the screws 46 are made, a concurrent operation of means shown in FIGS. 1 and 2 is effected to detect and indicate the electrodes position. Comprising this detector means is an inverted, conical shaped metal weight 55, to which a threaded rod 56, passing axially therethrough, is fixed by hexagonal nuts or the like. A hook at the upper end of rod 56 engages an eye bolt screwed into a centered hole in the lower end of the electrode, whereby the weight is suspended from the electrode. Operatively associated with this pendulum type structure are a plurality of screws 58, arranged about a cicumferential portion in the lower half of a tubular sleeve 59. An undercut portion on an upper part of sleeve 59 adapts it to fit snugly into an extended tubular opening 60 defined by a reduced portion of a fitting 61 screwed on to the lower rim of the principal tubular member 10 of the precipitator. A set screw 62 in a threaded hole passing through the reduced portion of fitting 61, acts to maintain the sleeve fixed to the precipitator structure. As best seen in FIG. 1, this connection locates weight 55 suspended from the electrode, mostly within the lower half of sleeve 59, and inside a circular array of contact points established by the tail ends of screws 58.

Contact screws 58 are electrically insulated from the conductive material of the sleeve 59, and retained for adjustment in respect to this sleeve, by a like plurality of insulator bushings 64. Each bushing is internally and externally threaded such that they are receivable in threaded holes circumferentially spaced about sleeve 59, and are adapted thereby to adjustably support within them the screws 58 for the latters coaction with weight 55. From the view of contact screws 58 seen in FIG. 2, which is of a section taken through line 22 in FIG. 1, it is evident that by the use of a screwdriver, the relative positions of the screws in their bushings can be preset to have their contact points define a nearly perfect circle about the axis of the tubular member 10. In this manner the sets of contact points facing each other can be spaced apart such that weight 55 suspended from an electrode that is nearly perfectly centered, does not touch any of the contact points. However, any significant misalignment of the weight from an axially centered position will cause it to engage a contact point. An indication of the electrodes misalignment is produced on a lamp 66, which as shown in FIG. 2, is one of a circular pattern of such lamps arranged on a panel board 68. Each lamp is located on the panel and numbered to correspond to the position of a screw 58 to which the lamp is electrically connected. Energizing circuits for these lamps which comprises the numbered connections, further include leads 70 joining one end of the lamp filaments to screws 58, a lead 71 connected in common to the other ends of the lamp filament, and a lead 72 connected to the electrode 26 at any suitable point thereon, and commonly grounded with or connected to a lead 73 in which are serially connected a switch 74 and a power source 75.

After sleeve 59 is appropriately secured within the opening 60 of the fitting 61, switch 74 is closed to prepare the energizing circuits to lamps 66. Z-mernbers 44 are turned aside to permit the lowering of electrode 26 with weight 55 hooked thereto, into the tubular member 10, until insulator 25 rests on the packing ring 24. Securing members 44 are re-positioned to place the pointed ends of screws 46 upon ring 50, and initial adjustments are made to screws 46 to clamp insulator 25 to the header flange 13. The character of the electrodes misalignment, if any, is quickly made evident on panel board 68 where an energized lamp indicates the relative disposition of the electrode. The final adjustments of screws 46 are then made by appropriately loosening or tightening individual screws as required, whereby insulator 25 is shifted or rocked upon the packing ring 24 to properly align the electrode. As a result, weight 55 becomes accurately centered between the contact points 58, whereby all lamps are deenergized since their circuits are interrupted by the discontinuities in the spaces between weight 55 and the contact points of screws 58. Thereafter set screW 62 is used to allow removal of sleeve 59 and the pendulum structure 55, 56, and their replacement by a cup-like enclosure constituting a particle collector trap for the precipitator.

In the modification of the top closure structure shown in FIG. 3, a packing ring 80 is received and maintained in an inclined groove 81 fashioned into the outer wall of a closure insulator 82. This insulator can be made as shown in the figure, in the form of a shell having the shape of a narrow pan on whose wide upper rim is positioned the flat metal pressure ring 50. Provisions made to fasten electrode 26 to insulator 82 include a threaded spindle 84 extending from the top end of the electrode, which is adapted to substantially fill a suitable central opening in the bottom portion of this pan-like insulator. High temperature asbestos washers 85 are placed on the spindle to contact the insulator surfaces, and hexagonal nuts 86 engaging threads on the lower end of the spindle are drawn up against washers 85 to seal the opening in the insulator, and to rigidly fix thereto the electrode 26. The high voltage wire connection 51, is clamped to spindle 84 by means of additional nuts 86. In the manner previously explained in connection with FIG. 1, a number of fastening devices including Z-members 44 and screws 46, are adjustably retained on flange 13, to act on ring 50 in the instant embodiments and clamp insulator 82 to the packing ring 80, whereby the opening in header flange 13, and the passage into tubular member are sealed.

The further embodiment of FIG. 4 is characterized by an inverted pan-shaped closure insulator 89, whose inner inclined wall 90 is grooved to receive and maintain a packing ring 91. Moreover, in this instance the precipitator is distinguished by a principal tubular member 92 having an extended upper part 93- whose rim 94 is downwardly flared to form an inclined skirt. As is evident in the showing of FIG. 4, insulator 89 fits over the opening of the tubular member 92 whereby packing ring 91 inside the insulator is wedged against the precipitators skirt portion 94. In the manner hereinbefore explained in connection with the embodiment of FIG. 3, electrode 26 is rigidly fastened to the upper flat portion of the insulator by means of asbestos washers and hexagonal nuts drawn up on a spindle which extends up from the electrode and passes through an opening in the insulator. Similarly, the high voltage wire '51 is also attached to the electrode by means of hexagonal nuts. However, the pressure ring 95 used in the instant embodiment is triangular in cross-section and is formed to lie upon the outer inclined wall surface of insulator 89. Since the largest diameter of the insulator exceeds any diameter of ring 95, the latter remains wedged above the open end of the insulator whereby the ring presents a flat surface 96 with which the fastening devices 40 and 42 are cooperatively related. A flange 97 shown in FIG. 4 as an integral part of the tubular member 92, is suitably extended to accommodate connections thereto which position and support fastening devices 40 and 42. Adjustments of these devices upon surface 96 of pressure ring 95, in accordance with the disclosure hereinbefore presented, are eminently effective to accurately align the electrode in tubular member 92, as well as to seal the upper opening therein.

The advantages of obtaining a consistently accurate centering of the discharge electrode in the general operations of an electrostatic precipitator become evident when it is recalled that the maximum voltage before breakdown can be achieved only if all radii from the central discharge electrode to the outer electrode are equal. If the discharge electrode was not so carefully centered some radii would be lesser in length than others and as a consequence the voltage at the breakdown point is accordingly reduced, and maximum utilization of the electrical potential is not available. A rigidly connected top closure such as is made available by the present invention, also eliminates the necessity for any fastening devices at the bottom end of the discharge electrode. Since the lower end of the precipitator tube is therefore unobstructed, it is free to receive the accumulation of the heavier particles arrested by the settling effect within the tube. This could not be done where the electrode joins the bottom of the precipitator in that the accumulation of the settled material would bridge between the cathode and anode parts and their connections, and cause an early electrostatic breakdown. On the other hand, the bottom of a precipitator according to the present invention can be structurally varied as needed to suit the anticipated accumulations, to avoid possible bridging of the materials and subsequent breakdown.

While preferred embodiments of the invention have been illustrated and described herein, it is understood that the invention is not limited thereby, but is susceptible to change in form and detail.

What is claimed is:

1. In combination with a casing forming an enclosure providing an electrode surface therein of an electrostatic precipitator in which gases and vapor are treated, a closure arrangement for an end opening in said percipitator comprising insulator means including a frustum of electrical insulator material, said frustum having parallel upper and lower substantially flat circular faces in each of which is formed a central cylindrical cavity, and an axial passage connecting the respective cylindrical cavities, a high voltage electrode component of said precipitator having a threaded reduced end portion thereof extending through said cavities and connecting passage, flexible packing material filling said cylindrical cavities, and a means for engaging said threaded portion of said electrode component and covering said packing in the upper cavity to draw said electrode component into a tight and compressed contact with said flexible packing whereby said electrode component is fixed to said frustum and said axial passage is sealed, a flange element fixed to said enclosure at said end opening thereof supporting said insulator means, said flange element having an inclined surface thereof bearing said insulator means, further flexible packing material maintained between and in contact with said insulator means and said inclined bearing surface, and means clamping said insulator means to said support element including a plurality of devices adjustably attached to said support element at separate, uniformly spaced apart locations thereon, and arranged to bear on said insulator means to position said insulator means and the electrode component fixed thereto with respect to said enclosure electrode surface, and to cause said further packing material to effectuate a seal for said end opening in said enclosure.

2. In the closure arrangement of claim 1, said frustum further having an angularly disposed surface substantially conforming to that of said inclined bearing surface of said support element, an annular groove in said angularly disposed surface of said frustum, said further packing material being retained in said groove in position to be compressed when said adjustable devices effectuate said seal in said enclosure end opening.

3. The closure arrangement of claim 1 wherein a rel-atively inflexible ring rests on said insulator means and each said device comprises a bracket, extending between said support element and said insulator means, having one end thereof connected to said support element to effect said adjustable attachment for said device, and another end thereof supporting a component displaceable therein contiguous to said insulator means whereby said component is positionable relative to said bracket to contact said ring and apply pressure thereto, and to said insulator means, and compress said further packing material to effectuate said seal for said opening in said en closure.

4. In combination with the closure arrangement of claim 1, an indicator, and means responsive to operation of said adjustable devices for positioning said insulator means and the electrode fixed thereto with respect to said enclosure and controlling the operation of said indicator, said indicator comprising a plurality of electrically energizable devices disposed in a predetermined arrangement, and said control means comprising a support attached to said enclosure, said support having adjustably secured thereto an arrangement of detector elements of electrically conductive material, whose positions therein correspond to those of said devices in said predetermined arrangement, an electrically conductive indicator operator element suspended from the free end of said electrode within said support means and displaceable with said electrode by said clamping means within paths defined between said detector elements, a plurality of separate circuit leads connecting said energizable devices to said detector elements in circuits comprising a circuit connection between said operator element and said energizable devices including a source of power, whereby engagement between the operator element and any one of said detector elements completes a circuit including one of said separate leads for energizing by said source of power, the one of said energizable devices corresponding to said engaged detector element.

5. The closure arrangement of claim 4 wherein said predetermined arrangement of a plurality of electrically energizable devices comprises lamps, and said corresponding arrangement of detector elements comprises screws having pointed tips thereof facing a common point, and wherein said indicator operator is a weight of a pendulum structure hooked on to the free end of s-aid electrode, and which is displaceable to engage said pointed tips.

References Cited by the Examiner HARRY B.

UNITED STATES PATENTS 7/ 1913 Cottrell 55-2 5/1921 Bradley 55-101 X 10/1926 Rowland 55-120 3/1931 Wintermute et al. 55-155 X 12/1931 Rowland 55-146 X 1/ 1941 Stevens. 7/ 1948 Newman et al. 340-282 X 7/1949 Unger 174-31 X 6/1952 Morris 340-282 6/1952 Dorrnont 174-18 X 5/1953 Street 174-152 7/195'4 Rafferty 220-46 X 10/1955 Cronin 174-152 X 4/ 1956 Wheatley 220-46 X 5/1956 Nicholas 174-19 7/1959 Putz l74l8 X 3/1960 Knapp 340-282 7/1962 Keane et al 174-18 X 9/1962 Barr 220-46 X 5/ 1963 Simpkins 220-46 X 11/1965 Zane 340-282 FOREIGN PATENTS 3/ 1922 Germany. 12/ 1924 Germany. 2/ 1931 Germany. 9/ 1932 Germany. 12/ 1925 Great Britain. 12/ 1936 Great Britain.

2/1952 Great Britain. 10/1955 Great Britain. 12/1958 Great Britain. 1/1963 Great Britain.

THORNTON, Primary Examiner.

R. F. BURNETT, D. TALBERT, Assistant Examiners. 

1. IN COMBINATION WITH A CASING FORMING AN ENCLOSURE PROVIDING AN ELECTRODE SURFACE THEREIN OF AN ELECTROSTATIC PRECIPITATOR IN WHICH GASES AND VAPOR ARE TREATED, A CLOSURE ARRANGEMENT FOR AN END OPENING IN SAID PRECIPITATOR COMPRISING INSULATOR MEANS INCLUDING A FRUSTUM OF ELECTRICAL INSULATOR MATERIAL, SAID FRUSTUM HAVING PARALLEL UPPER AND LOWER SUBSTANTIALLY FLAT CIRCULAR FACES IN EACH OF WHICH IS FORMED A CENTRAL CYLINDRICAL CAVITY, AND AN AXIAL PASSAGE CONNECTING THE RESPECTIVE CYLINDRICAL CAVITIES, A HIGH VOLTAGE ELECTRODE COMPONENT OF SAID PRECIPITATOR HAVING A THREADED REDUCED END PORTION THEREOF EXTENDING THROUGH SAID CAVITIES AND CONNECTING PASSAGE, FLEXIBLE PACKING MATERIAL FILLING SAID CYLINDRICAL CAVITIES, AND A MEANS FOR ENGAGING SAID THREADED PORTION OF SAID ELECTRODE COMPONENT AND COVERING SAID PACKING IN THE UPPER CAVITY TO DRAW SAID ELECTRODE COMPONENT INTO A TIGHT AND COMPRESSED CONTACT WITH SAID FLEXIBLE PACKING WHEREBY SAID ELECTRODE COMPONENT IS FIXED TO SAID FRUSTUM AND SAID AXIAL PASSAGE IS SEALED, A FLANGE ELEMENT FIXED TO SAID ENCLOSURE AT SAID END OPENING THEREOF SUPPORTING SAID INSULATOR MEANS, SAID FLANGE ELEMENT HAVING AN INCLINED SURFACE THEREOF BEARING SAID INSULATOR MEANS, FURTHER FLEXIBLE PACKING MATERIAL MAINTAINED BETWEEN AND IN CONTACT WITH SAID INSULATOR MEANS AND SAID INCLINED BEARING SURFACE, AND MEANS CLAMPING SAID INSULATOR MEANS TO SAID SUPPORT ELEMENT INCLUDING A PLURALITY OF DEVICES ADJUSTABLY ATTACHED TO SAID SUPPORT ELEMENT AT SEPARATE, UNIFORMLY SPACED APART LOCATIONS THEREON, AND ARRANGED TO BEAR ON SAID INSULATOR MEANS TO POSITION SAID INSULATOR MEANS AND THE ELECTRODE COMPONENT FIXED THERETO WITH RESPECT TO SAID ENCLOSURE ELECTRODE SURFACE, AND TO CAUSE SAID FURTHER PACKING MATERIAL TO EFFECTUATE A SEAL FOR SAID END OPENING IN SAID ENCLOSURE. 